The present invention relates generally to fuel rails for the fuel system of an internal combustion engine, and more particularly to dampers located within the fuel rails.
A fuel rail supplies fuel to fuel injectors, which in turn inject fuel into combustion cylinders in internal combustion engines. Typically, each fuel injector injects fuel in pulses that are controlled to maximize the efficiency of the combustion process within the cylinder. These pulses of injected fuel introduce pressure fluctuations into the fuel contained within the fuel rail. These pressure fluctuations create various problems, including improper fuel distribution to the injectors, which results in inefficient engine operation, and fuel line hammering, which results in vibration and noise.
Fuel rail dampers are employed to dampen the pressure fluctuations within the fuel rail. One type of fuel damper is situated completely within the fuel rail and consists of a sealed chamber which is designed to be tuned to substantially dampen the pressure fluctuations within the fuel rail. Prior art relies on various methods of mounting this pressure damper within the fuel rail.
U.S. Pat. No. 5,617,827 discloses a damper positioned and held within the damper using two damper supports. One of the supports is keyed and corresponds to a positioner in the circumference of the fuel rail to prevent rotation of the damper. These support structures do not allow relative motion between the damper assembly and the fuel rail but are often difficult and expensive to make due to the intricate slots, grooves and keys required to receive the damper and maintain proper positioning.
U.S. Pat. No. 6,205,979 uses two springs at each end of the damper assembly to suspend the damper within the fuel rail. These springs are crimped inside a tube. The crimp which retains the spring also serves to seal the damper chamber from fuel. Especially in high production volumes, it is difficult to insure that this crimp provides a seal sufficient to keep fuel out of the inside of the damper chamber. Furthermore this system suspends the damper assembly within the fuel rail on two sprung mounts, allowing relative movement of the damper assembly with respect to the fuel rail in response to fuel pulsations, engine vibrations or other accelerations. This springing motion within the rail can cause undesirable contact between the damper assembly and features within the fuel rail (such as fuel injector ports), causing wear, noise and the production of metal shavings and fragments which can clog injector ports.
It would be desirable, therefore, to provide a mounting system for fuel dampers with a fuel rail which reduces relative motion between the rail and the damper assembly yet which are easy to produce and assemble.
The present invention overcomes the disadvantages of the prior art approaches by providing a fuel rail assembly comprising a fuel rail and a damping assembly contained within said fuel rail. The damping assembly is comprised of a damping chamber having a first end, a second end, and a hollow member. The first end and the second end each are formed by crimping the hollow member in a manner such that the cross-sectional outline of the first end and the second end does not extend beyond the cross-sectional outline of the hollow member. The damping assembly further comprises at least one clip fixed in relation to either the first end or the second end. The clip has at least one finger, which contacts the inner wall of the fuel rail. The finger or fingers are disposed on a first side of the damping assembly and the second side of the damping assembly is forced into contact with the inner surface of the fuel rail opposite of where the finger or fingers are in contact with the inner surface of the fuel rail.
A single clip at one end of the damper can be used or clips at each end of the damper assembly can be used. These clips can be attached to the fuel rail by crimping, clipping, adhesive bonding or riveting.
The fuel rail may have structural features which cooperate with the finger or fingers to lock the damper into place longitudinally and/or rotationally within the fuel rail.
The finger or fingers may be designed so that they are plastically deformed to contact the inner surface of the fuel rail once the damper assembly is inserted into the fuel rail.
It is an object and advantage that the present invention substantially maintain the relative position of the damper assembly within the fuel rail in an effective and cost efficient manner.
These and other advantages, features and objects of the invention will become apparent from the drawings, detailed description and claims which follow.